Expansible mandrel



Oct. 6, 1953 v J, c. WEIQEL 2,654,413

ExPANsIBLx-z MANDREL Filed March 24. 1951` 2 sheets-sheet 1 JC [V5/DEL f a a :2m Y n 7 .w 2 s V/f/J///w/Qwvv mwa/ IN VEN TOR ATTORNEY Oct. 6, 1953 J. c. WEIDEL 2,654,413

EXPANSIBLE MANDREL Filed March 24, 1951 2 Sheets-Sheet 2 Patented Oct. 6, 1 953 STATES P EXPANSIBLE MANDREL Joseph C. Weidel, Bonita, Calif., assigner to Rohr Aircraft Corporation, Chula Vista, Calif., a corporation of California Application March 24, 1951, 'sensi No. '217,349

In the manufacture of such articles, close tolerances must frequently be held, as for example, in the inner or outer diameter of a cylindrical sleeve. The general requirement of low tooling costs, in many cases prohibits the holding of such tolerances when the article is initially formed, since the development costs of forming equipment are in direct proportion to the degree of precision it is required to have. Consequently, it is common practice to form such an article relatively orudely in the initial operation, resorting to a secondary operation to bring it into its finished shape and size.

It is also well known, that in the case of welded tubular articles, the metal temperatures produced by the welding operation tend to distort the article, necessitating a iinal truing operation, where any appreciable accuracy is required.

The principal object of this invention is to fulfill the needs arising from the problems above described.

Another obiect is to provide an expansible mandrel which is capable of increasing the diameter of tubular articles within certain limits.

A further obiect is to provide a device of this class having associated adjustment means which may be easily and quickly controlled by the operator. v

A still further obiect is to provide a device of this class which will not score or otherwise mar the surface of the workpiece.

Other objects will appear in the description as hereinafter more fully set forth.

For a better understanding of the invention, reference is made to the accompanying drawings in which: v

Figure 1 is a plan view of a mandrel embodying the invention, showing themajor portion thereof in its unexpanded position and the remainder in its expanded position,

Figure 2 is a vertical section of Figure 1 taken along the line II-II showing the mandrel in its unexpanded position,

Figure 3 is a vertical section taken along the lineIII-III of Figure 1 showing the mandrel in its expanded position,

Figure 4 is a perspective view'of one of the metal blades of the mandrel and,V

Figure 5 is a cross section of Figure 4 taken along the line V-'V.

3 Claims. (Cl. 153-80) The mandrel Il comprises a ring of generally sector-shaped steel blades I2 which are held together in assembled relationship by a body I3 composed of rubber, Neoprene, the polychloroprene having the molecular composition C4H5Cl or other known elastic material which is resilient and assumes its original shape upon the removal of a force which has deformed it. Each blade is shaped as shown in` Figures 4. and 5, having a tapered inner edge I4 and a vertical tubeengaging redge I5 which terminates below in a step I6. Projecting outwardly beyond step I6, 4the lower end of the blade has a guide foot II terminating in a vertical edge I8. The top edge I9 and bottom edge 2li o f the blade are horizontal and parallel to the top edge 2l of foot I'I. The material of the blade increases in thickness from its inner edge Ill to its outer edge I8 so that `when a set of the blades is arranged around a ccentral axis 2z (Figure 2), the edges I4 together form a conically shaped surface 23 and the edges I5 together form a cylindrical surface 24.

Eachblade has a pair of grooves 25 cut in its opposite faces and a series of spaced apart holes ,26 connecting these grooves. In the assembly of the mandrelthe resilient material enters these grooves and holes and becomes rmly bonded to the blades duringthe vulcanization or bonding process for the resilient material. Since the resilient material in holes 2t connects the vertical strips of similar material located in the grooves 25 together, a continuous ring of the resilient material is provided within the mandrel to connect the blades thereof and maintain them in symmetrically assembled relationship while permitting the slight separation of the blades incident to the expansion of the mandrel. The mandrel is mounted on a horizontal table 21, the upper surface 28 of which is smooth to permit .the sliding engagement of the bottom faces 2E of blades I2.

Operation of the mandrel is effected by a plunger 33, the upward thrust of which is taken up by a retaining ring 29 secured to the table 2l by a set of bolts 3Q. Ring 29 has an inwardly extending flange 3 I, the lower surface 32 of which is smooth topermit sliding engagement with the top faces ZI of the feet II.

The conically shaped surface 34 of the plunger 33 vhas .the same taper as the edges I4 of blades I2, and is adaptedto bear against the conically shaped surface 23 formed by those edges. At its lower end the plunger has aprojecting ange 35 adaptedto abut' against the bottom'face 3B of carry a piston (not shown) movable within a.'

vertical cylinder to which uid under pressure may be admitted to operate the pistoir a well known manner. It will be understood. however.; that any other reciprocating power member'may be used to actuate rod 39.

To operate the mandrel, thetube T to be expanded is slipped over the mandrel fl and Iowered until its bottom edge rests upon the steps:

I6 which then support its weight. Push rod 39 is then caused to rise until the-upperportion of conical-cam face 34y engages. a portion of conical surface-.23. If at this time.. the vertical axis. 22 of mandrel Il is not in alignment with the axis of cam face 34, a slight further rise of plunger 34 will apply Vpressure to several of the blades I'2 at one side of the mandrel only'. The sdewise component of.' this pressure .causes the entire mandrel. Il to slide a. small distance along; the surface 28 of table 2T until the axis 22' of" the mandrel comes into alignment with the axis of cam face 34. The mandrel in this position .is shown inFigures l and 2;.the blades f2l of Figure 2 and those shown insecto!" A of Figure 1 .being represented in their innermost position .before expansion of tube T has commenced. Still furjther riseof. plunger 33' causes all the blades f2 to move radially outward and deforrn tube 'I' into truly cylindrical shape if it. was not cylindrical when placed on the mandrel. If the tube was cyl'indricaly when. placed on the mandrel, the expansion of the mandrel causes .its deformation and an increase in its diameter. The rise of plunger 33 isVV continued until the expanslonrof the mandrel expands tube Tto the desired diameter, the blades l2 separating slightly one from. anotherr during the expansion and the rubber Vi3d-:tween the blades Ybeing placed under tension- When the flange 35 abutsY against the bottom 36 of table il, the rise of plunger 33 is arrested' and the man* drel is in its fully expanded condition, as shown in Figure 3. `Several blades l2 of themandrel in this condition are shown in sector B of Figure l.

Furthermore just as the rise of plunger 33 is stopped by flange 35, Vthe hydraulic piston (not shown) attached to push rod 39 .comes to the end of its stroke. Under these conditionsA the tube T has been expanded to the maximum diameterV within the range of the mandrel.n If Va smaller diameter of tube is desired, the ,operator loosens lock'bolt lll and' screwsv plunger 33 down on rod 39 by the proper amount, before expansion oi the tube is commenced, and then tightens lock bolt 40. UponV again operating the mandrel, when the piston reaches the upper end oi its stroke, plunger 33 will not rise so high and ange 35 will notreach the level ofthe bottom 36 of table 21. This is explained by the fact that the hydraulic cylinder (or other actuating means) remains at-a fixed distance from the top .of the table.Y By. thus adjusting the position of plunger 33 on push rod 39, tubescan .be expanded with precision to any desired diameeter within the capacity of the mandrel. Upon lowering plunger 33, the. blades l2 are pulled inwardly by the rubber of body I3 which is under tension until the faces of adjacent blades are in contact with each other and the mandrel is in its initial condition. The iinished tube T is no longer gripped by the blades and may be readily lifted from the mandrel.

My invention may be embodied in other specific' farms without nom the spirit or essential characteristics thereof. The present embodiment, as above set forth, is therefore to be considered in all respects as illustrative and not restrictive, the scope of my invention being indicated by the appended claims rather than by thefioregeing description, and all changes which eomewithin the meaning and range of 'theclaims are therefore intended to be embraced therein.

I-laving thus described my invention, what I claimeias Anew and useful and desire to secure by Letters Patent is:

1.. A.. hollow mandrel adaptedtcbe. expanded by' the Yconical cam surface 'oi'a power-operated plunger, comprising: Ya-plurality of radially disposed rigid bladesthe opposite faces ofeach blade being full. contactwith the. facesof the adjacent blades, each of said, faces being provided with a groove extending lengthwise the entire length of the face. .the inner edges of said blades extending td -forma conical surface adapted te bevengaged by said cam surface and the outer edges of said. bladesforming. a. cylindrical surface adaptedtoV engage-theinner surface of a tube tobe deformed.; aV body-ofresilient rubber-like material disposed between. said blades extending into andllling said grooves and being attached tothe walls thereof whereby said blades are yieldingly secured together 2r A mandrel as .claimed in claim 1;. in which said blades are Vprovidedrvith spaced apart openings near the upperandV lower edges thereof extending through said blades and opening into said grooves, said resilient. rubber-like material passing through.V and'. lling .said openings. e

3.. A Ahollow mandrel adapted to be. expanded by the conical cam surface of a verticallymovable power operatedplunger comprising, in combination; `:a.,plurality ofA radially disposed rigid metal bladesL the opposite faces vofeach blade being in full contact with the faces. ofy the adjacent blades, each of said. faces. being provided with a groove. extending `lengthwise the entire length of the face, the inner edges of the blades extending to formY a conical surface adapted to be engaged by said cam. surfaeaf-each'blade having a long verticalportion arranged to. engage and expand the interior-of a vertical tube, a first step projecting. outfrom the lower` end ofV said vertical portion and a second step projecting out from the lower .end of said first step, said rst steps forming a series of spaced. apart supports adapted to engage the lower end of the tubeat many regions Vand support .the entire ,weight of the tube, theupper ends of said second steps lying in a horizontal plane; abody of resilientV rubber-like. material disposed between sadblades,Y filling said grooves and being at-f tached to the walls thereof 4vvherebysaidblades are yieldingly secured together; an .annular ree taining ring having a smooth horizontal surface projecting in over said second stepsand along which said second steps are slidableV in response to the upward movement of the plunger, thetop of said retaining ring .being disposed .out ofthe path of travel of the lower `end-oi Vthe tube as the tube is expanded; and means for securing said ring in a. fixed horizontal position.

JOSEPH C. WEIDEL.

Number Name Date Tully Sept. 14, 1880 Knapp Apr. 22, 1902 w Passat Dec. 22, 1908 Williams Apr. 11, 1922 Myers Mar. 3, 1925 Miller June 22, 1926 Number 6 Name Date Burke May 29, 1928 Rode Feb. 24, 1931 Spatta. Sept. 5, 1933 Mason Dec. 19', 1933 Lovely Apr. 18, 1933 Green Oct. 25, 1938 Gibbons Mar. 12, 1940 Stoner Apr. 18, 1944 Brace Mar. 28, 1944 Murphy June 6, 1944 Morrill Feb. 15 1949 Le Count Mar. 6, 1951 

